Brown’s Folly Nature Reserve consists of 91 acres of land on the hillside overlooking the valley of the River Avon about half a mile south-east
of the village of Bathford. It is owned by the Avon Wildlife Trust and has been designated as a site of special scientific interest (SSSI) because of
the Middle Jurassic rocks, plants, wildlife that can be found there.
Extensive limestone extraction on the reserve, largely by mining, was carried out in the past, the stone being used for building and known as Farleigh Stone. This activity, long discontinued, has left the rock exposed at many sites enabling it to be examined. The study of the different layers (strata) of rock and the fossils they contain has made it possible to establish when they were formed and to build up a picture of what the area would have looked like at the time. A sediment of ooids, sometimes mixed with shell material from the organisms living in the sea, would have collected on the sea floor and eventually become cemented together to form a rock. As conditions such as the depth of the sea varied, different types of sediment formed to be later consolidated into the different rocks seen today on the reserve.
The rocks seen on the reserve are from the Chalfield Oolite Formation and the Forest Marble Formation A number of different rocks make up each group and these can be seen in the 'Sequence of Rocks at Brown's Folly'. In this table, the rocks are set out in sequence, together with their total thickness and an indication of the rocks that can be seen at each site. More information on the various rock types is given later in the guide.
Most of the sites are easily accessible but there are some steep slopes and rough paths.